My book is $79$ pages. I have been reading $10$ pages each day. There are $9$ pages left to read. How many days have I been reading the book?
Answer: $\text{Pages read}$ $\text{Pages left}$ $9$ $10 \times {\text?}$ $79$ I have read $79-9=70$ pages. $70\div10=7$ I have been reading the book for ${7}$ days.